(g∘f)′(x)=f′(x)⋅g′(f(x))(g\circ f)'(x)=f'(x)\cdot g'(f(x))(g∘f)′(x)=f′(x)⋅g′(f(x))
dgdx=dgdfdfdx\frac{dg}{dx}=\frac{dg}{df}\frac{df}{dx}dxdg=dfdgdxdf